The federal Centers for Disease Control and Prevention has confirmed that the Alamosa city water supply is indeed contaminated with salmonella.

Salmonella had been suspected, but a preliminary analysis revealed only that there was a harmful organic compound in the water system.

David Svaldi, president of Adams State College, revealed the findings in an open letter today.

Officials at the state health department laboratory said today that they have confirmed that five out of six water samples taken from various areas around Alamosa tested positive for the bacteria.

The Colorado Department of Public Health and Environment issued a bottled-water advisory for the town Wednesday after tests showed bacteria in the city water supply.

The crisis management team has logged 217 cases of illness out of the 10,000 people potentially exposed to the water. Nine people have been hospitalized.

Alamosa uses a deep well that is not chemically disinfected.

The system will be flushed and disinfected with chlorine — a three-stage process that could take more than a week, state officials said. Chlorination equipment will remain in place after the flushing process.

Flushing the well system will begin at 9 a.m. Tuesday, and it will make even boiled water unpotable.

It could be two weeks before Alamosa residents can drink from the tap again.

Companies have been donating bottled water, and the governor called on the Colorado National Guard to help.